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 Post subject: Where to dig a snow pit?
PostPosted: Tue Jan 11, 2011 11:53 pm 
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Location: Cottonwood, UT
I just went to a Science of Avalanches seminar at REI where Bruce Tremper (A UAC forecaster) was hosting. Somebody asked a question about digging snow pits and where are good locations to do it. He said all of these tests will work even in flat meadows. Referring to the CT, ECT, shovel tilt. He said especially the ECT works well. This shocked me because I was always under the impression that always had to get out on a slope (Potentially dangerous at times) with a similar elevation and aspect to the slope you want to play on.

So I raise the question, where have all you splitters been digging pits? And how do you ensure that the slope you're digging on won't collapse on you? Where have you found to be effective? What indicators do you look out for before walking out on a slope and start digging?

I know there are ways to stay relatively safe by top roping and rappelling and such but I know most people don't carry a rope with them when travelling in the BC so I'm more curious about the more typical methods.


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 Post subject: Re: Where to dig a snow pit?
PostPosted: Wed Jan 12, 2011 5:38 pm 
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Location: New Castle, Colorado
Perhaps the question is out of context here. You stated, "Bruce said,

Quote:
Bruce Tremper (A UAC forecaster) was hosting. Somebody asked a question about digging snow pits and where are good locations to do it. He said all of these tests will work even in flat meadows. Referring to the CT, ECT, shovel tilt
.

So correct me, if I am wrong here, but it sounds like your asking, "Will snowpit analysis on a flat meadow will yield, similar results as to the slope I want to ski?

Bruce Tremper in his book Staying Alive in Avalanche Terrain and on the following website see, (excerpts from Bruce's book: http://www.fsavalanche.org/Encyclopedia/snowpit.htm

Quote:
Where to dig a snowpit:

Where to dig a snowpit is probably more important than how to dig one. Choosing a representative location is an art, and art is difficult to describe.

Dig it on a slope most representative of the slope you are interested in but without putting yourself in danger. Often you can find a small representative test-slope--one that won't kill you if it does slide. Or, you can work your way into progressively more dangerous terrain. For instance, if a snowpit on safe terrain gives you a green light, then it gives you the confidence to dig another one on more dangerous terrain. Green light there? Then, move onto even more dangerous terrain, and so on. Never dive into the middle of a dangerous avalanche path without first gathering lots of additional data about the stability of the slope.

Don't dig it along ridgelines where the wind has affected the snow--a common mistake. Although sometimes the crown face of an avalanche may break right up to the ridge, the place where we most often trigger avalanches is 100 or more feet (30 meters) down off the ridge. Avoid thick trees because conditions are often quite different than on open slopes. Avoid compression zones and tension zones. Avoid places where people have compacted the snow.

Bottom line:
LOOK FOR NEUTRAL, OPEN AREAS AT MID SLOPE WITHOUT WIND EFFECTS.


So what I get from Bruce Tremper's quote is that "the test(s) work on flat terrain. That I can use the above snow pit tests or what Bruce Tremper call "active tests", and look for the "Five Red Flags" (see http://jeremyjones.net/2009/12/five-red-flags/ to get the greenlight to move on to onto more dangerous terrain(stated above) and test again. Your always looking for a reason to "back-down" as Jermey Jones says in his blog "http://blog.jonessnowboards.com/2010/12/avalanche-awareness-just-say-no-with-jeremy/ and http://www.tetongravity.com/videos/Deeper-Backing-Down-Reccosafetytipswith-Jeremy-Jones-955089.htm

So I would not hang my on one snowpit in flat terrain, unless I get a "red light" from such snowpit test(s) (like a repeatable results, example: like a failing on a slab wide spread buried surface hoar" or other "red lights". but that would start testing in flat terrain, and if I get a green light to continue, testing along the way up to the line, I want to ride and "test' on the way out as well.

Still if, Bruce Temper's statement is contrary to my interpretation. Ask him directly and post his quote here.

As far as a belay rope goes; I would like to know what people are using. What is the smallest diameter of rope, I could use for a static belay and what length would you carry?

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 Post subject: Re: Where to dig a snow pit?
PostPosted: Wed Jan 12, 2011 6:19 pm 
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Location: New Castle, Colorado
Here is an interesting report of a snowpit showing stability, when the Avalanche Center has rated the avy danger as in the red (High, level 4) for two days , by Lou Dawson: See "Here in Colorado, Avy Danger in the Red Zone" http://www.wildsnow.com/4102/red-zone-avalanche-danger/

Well worth reading in the context of what, I have previously stated above, do not hang your on one test. or as Bruce Tremper says, "Remember, Never get married on the fist date; never base your whole stability evaluation , on one piece of information".

Lou's story is a good example of following Tremper's axiom.

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 Post subject: Re: Where to dig a snow pit?
PostPosted: Thu Jan 13, 2011 7:22 am 
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He might have been referring to a recent study that did multiple ECT's on angles something like 28 degrees and up maybe less maybe more, can't remember. They were done on an aspect that holdiing a reactive persistent weak layer and they found the results to be the same whether it was 28 degrees or 38 degrees. Suggesting that you can get the same data without putting yourself in danger on steep exposed slopes. Thanks for posting up whitepine, fun to talk about this stuff.


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 Post subject: Re: Where to dig a snow pit?
PostPosted: Fri Jan 14, 2011 3:33 pm 
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Location: 802
there's a really good discussion over on tgr about snow pits here. definitely worth a read.


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 Post subject: Re: Where to dig a snow pit?
PostPosted: Tue Jan 18, 2011 11:01 pm 
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Joined: Thu Jan 14, 2010 1:28 pm
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Location: Cottonwood, UT
Thanks for the input guys. I've just started reading through Tremper's book for the 2nd time, since the first time was like drinking from a firehose. So thanks for the advice and reminders. This year I'm going to start practicing all these tests a little more frequently than I did last year so I really get good reading what the snowpack is saying.

Another interesting thing Bruce said when I talked to him was that he likes to choose a spot just uphill from a tree so if it slides he can make a grab for it.

Powder_Rider - I think you are right on. These tests can be done in flatter terrain but green lights give you the go ahead to work your way into steeper terrain.
Powder_Rider wrote:
As far as a belay rope goes; I would like to know what people are using. What is the smallest diameter of rope, I could use for a static belay and what length would you carry?

I'd also like to know this if anyone has any advice.

Thanks for all your posts.


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 Post subject: Re: Where to dig a snow pit?
PostPosted: Mon Jan 24, 2011 10:29 pm 
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Location: New Castle, Colorado
Quote:
He might have been referring to a recent study that did multiple ECT's on angles something like 28 degrees and up maybe less maybe more, can't remember. They were done on an aspect that holdiing a reactive persistent weak layer and they found the results to be the same whether it was 28 degrees or 38 degrees. Suggesting that you can get the same data without putting yourself in danger on steep exposed slopes.


"Utah" your assertion is correct;
Quote:
"Suggesting that you can get the same data without putting yourself in danger on steep exposed slopes"
"Suggesting that you can get the same data without putting yourself in danger on steep exposed slopes". I asked Brian McCall at last week's Avalache Awareness Seminar.

Brian confirmed, BUT Aspect, Elevation and Proximateness to the "choosen" slope are also considerations. Brain noted (paraphrasing) that "number of taps might be different on different degree of slope angle, but the numbers are not as important as the result of failure, collapse and propagation. Watch the layers for fractures,failure, collapse and propagation as you tap.

See http://www.youtube.com/watch?v=crwvFn67e5Q&feature=related where Cam Campbell, Public Avalanche Forecaster for the Canadian Avalanche Centre notes the important's "characters of the fracture/failure

Please contact your local Avy Forecaster /AIARE Instructor, and confirm "Snowpit location". There are two many details to get this second-hand from a blog. I am going to take a refresher "AVY 2" course, just to get confirmation and hands-on experience.

Brian gave an example of entering Aspen "side-country", where you access the bowl from a ridge. Where the lee side of the ridge you could dig pit and all would pit analysis would be good, but down in the start-zone the snowpack was dangerously shallow and skier avalanche was triggered. The context here; entering via side-country does not allow for a complete analysis of the snowpack clues, as would starting one's tour from well below the choosen slope. I am using the above illustration to show that you can't hang your hat with just snow-pit analysis alone.

FYI: I might have avy-training, but I have very little "backcountry "backcountry street smarts" street smarts" experience. Please take my comments as an inference to learn more and not fact. I'm not an expert.

Speaking "backcountry avy street smarts" Read Snowstruck by Jill Fredston. It is a great read on the human-side of avalanche forecasting. I had the opportunity to take an avy course with from Jill and Doug Fesler, in 1987 at Hatcher's Pass, AK. A lot has change, since then!

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Venture Storm R 163 (2010), Dynafit Binding/Sparks Adapter, Scarpa F1 Boots, Bomber Sidewinder Bindings * Prior 172 Fissile (2012) Dynafit Binding/Sparks Adapter


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